While tree diseases often thrive in spring, it is important to remember that proper care year-round can make a big difference in managing these issues. Some simple practices now can help combat disease. One good example is autumn and winter care to help control fire blight. Caused by the bacterium Erwinia amylovora, fireblight commonly infects pear, apple, hawthorn and quince.
Symptoms of Fire Blight
The disease gets the name “fire” blight because severely infected plants will have blackened or dark brown branches and foliage. Plant tissue can look as if it has been scorched or burned. The affected branches also often form a shepherd’s crook at the tip.
How Fire blight Spreads
Bees and wind-driven rain spread new infections during spring. These infections progress into the twigs and toward the main trunk. Once infected, cankers on trunks and branches can persist, where they serve as a source for future infections. Left untreated, cankers can completely girdle the cambium tissue. The result is the death of large branches or entire trees. The bacterium is active during the moist and humid weather of spring. After spring, the bacterium is normally dormant. However, symptoms in infected tissue can continue to worsen during this time.
Action to Combat Fire Blight
Management of fire blight requires sanitation and prevention. Pruning infected tissue should be performed when the bacterium is dormant and spread of disease has ceased. Please note that on highly susceptible trees and rapidly advancing infections, pruning below the branch cankers should be performed immediately to reduce severity – even when the disease is active.
Any leaves that have fallen from infected trees should be bagged and removed to help minimize re-infection.
Preventive treatments can also help protect healthy tissues from new infections. It is rare to get complete control over any plant disease but limiting infections through sanitation and prevention will limit dieback and avoid major infections that often lead to plant disfigurement or mortality.